| Copper is an important nutrient element. As the one of essential microelements which plays an important role in plant growth, widely existing in plants. During copper mine were deeply exploited, industrial "three-wastes" emissions were disposaled easily and the cupric pesticides were widely used in agricultural industry, the content of copper in soil is out of limits that has attracted people’s increasing attention. As copper has accumulation in plants, excessive copper in plants would have negative effects on plant growth, quality and yield. Sometimes, reduction of output and total failure would happen when copper was badly excessive. The health of human body would be affected when excessive copper entered human body through food chain. The negative effects to plants were various, the effects on growth, photosynthesis, membrane permeability and the activity of autioxidant enzyme were reported.Chinese cabbage is one of most popular vegetables in China. However, the quality of Chinese cabbage is affected by black sesame spot Furthermore, the products export industry and economic incomes of Chinese cabbage are influenced. Black sesame spot were appeared on petiole and veins areas with a large number of black or dark brown sesame spots mainly in petioles of epidermal cells which influenced economic quality of Chinese cabbage. For now, there was no report about the pathogenesis of black sesame spot. Copper enrichment in Chinese cabbage influenced the degree of black sesame spot was reported without actual experiments and verify. When Chinese cabbage were planted in orchard and cupric pesticides and bordeaux mixture were widely used at the same time, black sesame spot was more likely to happen. Copper content was very high in these soil even reaching12.7mg· kg-1.Chinese cabbage lines with different resistance to black sesame spot were selected as materials, to study the effects of different concentrations of copper on black sesame spot, the index of growth and disease resistance, physiological and biochemical mechanism of Chinese cabbage black sesame spot, with treatment of foreign copper in soilless nutrition solution culture and soil culture conditions on Chinese cabbage, in order to provide basis theoretical for the prevention of Chinese cabbage black sesame spot. The main results are as follows:1. Using C24,03B9as the test material under hydroponic conditions, and on the condition of soil cultivation using87-114, Qingyan Juhong No.1, Qingyan Zao No.9, C24,03B9as the test material, the occurrence and resistance evaluation of black sesame spot were investigated and evaluated after the treatment of exogenous copper imposed on Chinese cabbage seedlings. The results showed that, after the copper treatment, the condition of black sesame spot has been significantly promoted, and the number and occurrence area of black spots in petiole were positively correlated with copper concentrations. It indicates that copper could induce the occurrence of black sesame spot in Chinese cabbage.2. The effects of copper treatment on the growth index and matter content of Chinese cabbage were investigated. The results showed that, after the treatment of copper on Chinese cabbage seedlings under hydroponic conditions, the whole fresh weight and root fresh weight of Chinese cabbage were promoted by low copper concentrations, whereas inhibited by high concentrations, and different lines of Chinese cabbage have different thresholds for copper. The content of leaves green pigment were decreased by copper concentrations, but the influence of copper on each pigment content is not have larger difference. With the increase of copper concentration, the content of copper in leaves are increasing, but the content of copper were remained constant substantially during the processing treatment. The lines with were kept the higher content of calcium, and the content of calcium in lines with serious disease occurrence were decreased.3. The effects of copper treatment on the activities of glutamine synthetase (GS), glutamate dehydrogenase (GDH) of nitrogen metabolism enzymes in the petioles of Chinese cabbage seedlings were investigated. It was found that, the activities of enzymes had significant influence by copper concentrations, and the normal nitrogen metabolism becomes disorders. As the copper concentration increased, the activities of GS were significantly lower compared with the control, while the activities of GDH were significantly increased at the later stages of processing. It indicated that the disorders of nitrogen metabolism caused by the exogenous copper are interrelated to the occurrence of black sesame spot.4. The effects of copper treatment on the activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), polyphenol oxidase(PPO) in leaves and the contents of total phenolic compounds and lignin in petioles of Chinese cabbage seedlings were investigated. The results showed that as the increase of copper concentration and the extension of processing time, the activities of PAL, TAL, PPO in leaves and the contents of total phenolic compounds and lignin in petioles of Chinese cabbage seedlings were significant changed. The activities of PAL, TAL, PPO in leaves and the contents of lignin in petioles of lines seedlings with high resistance were obviously higher than that of lines with high sensitivity. The contents of total phenolic compounds in petioles of lines seedlings with high resistance were accumulated more when the concentration of imposing copper rise, whereas the lines with high sensitivity were dropped off It indicated that the activities of key enzymes and contents of secondary metabolic products in phenylpropanoid metabolites of Chinese cabbage seedlings which imposed treatment of copper are closely related to the occurrence and level of resistance to black sesame spot. |
PDF Full Text Request